A semiconductor packaging technology for protecting a chip formed on a silicon wafer from external environment and connecting the chip to circuit components and a substrate has been developed remarkably. Recently, an insert mount package such as a dual in-line package (DIP) is nearly unused, but other surface mount packages such as a small outline package (SOP), a quad flat package (QFP), a thin small outline package (TSOP) and a paper thin package (PTP) are prevalently used as a semiconductor packaging technology.
Meanwhile, semiconductor devices have a tendency toward miniaturization and large integration; and, as a result, a packaging technique to modularize the surface mount package is continuously investigated.
However, there exists a difficulty in realizing miniaturization and large integration of the surface mount package module. Therefore, a chip scale package is required, in which a package miniaturized to have almost the same dimensions as a chip to be mounted therein.